350 intake/carb suggestions

[nixtux]

Another weird thing. There was this wretched sound, kind of like a loose belt but not quite as high pitch. That went away after the pump and oil was changed. Not exactly thrilled about that one. But at least it went away because if that was a sound from the gas, I know when it started and can determine the miles at just over 50.

I manually applied pressure to the old fuel pump and got a similar noise. I suspect the noise was the fuel pump.

[nixtux]

I finally got a deposit in my account, so I'm going to the parts store to get the remaining parts in the morning when it clears.

I'm not sure if I need to have valve lash or not. I attached some pictures of the valve springs. Any advice there would be great.

I also attached a picture of the front pass side exhaust port (I think it's exhaust anyway). It it's pretty nasty. Is there anything I should get to clean it up?

Thanks!

[nixtux]

Done. It's alive. Haven't done much driving yet, but it runs great! The timing is almost spot (I haven't taken the light to it yet, but it has loads of power it didn't have before.) It's not sputtering any fluid from the exhaust. And it pretty much breaks a guys neck when you punch it. It even breaks between gears again.

The only weird thing, when I was putting the carb back on a spring fell out. I couldn't figure out where it went so I just put the carb on. In any event, it idles really low but once it warms up it's fine. I'm buying a reman quadrajet next week so I figure who cares. I'm pumped that it started up first try and seems to run great. Also a knock that was in the motor (I was told it needed a valve adjustment) went away. From that, I take it I adjusted them correctly.

Thanks for all the help on this. I really don't think I could've done it without some of the advice on here.

Thanks again!

[Axe_1]

Awesome nixtux! Glad to hear it's running good again. I would say that the screech was 100% bad fuel pump. Hopefully you got the rockers adjusted decent. With hydraulic lifters you have a small amount of room for error. With solid lifters you don't really have any.

That nasty port looks like a water jacket to me. The crud is just deposits from the water. I would have scraped out what I could and moved on. They are always ugly. If you look at the first head pic, the Intake Ports are on the left and the Exhaust Ports are on the right. They still have the headers attached over them.

A rebuilt Q-Jet sounds like the right way to go for your setup. That intake should work fine besides being heavy and limiting your high RPM's but will work better for low RPM torque. That's what you need on the street anyway so you're good.

Which LocTite did you get? (Red,Blue, etc) It's a little late now but what I use on Intake & Water Pump bolts in the Permatex Non-Hardening type. It's dark brown and feels like wet modeling clay when you put it on but keeps the bolts in place and liquids from oozing up the threads.

Axe

[nixtux]

I got the red loctite. Hopefully they don't come loose again. So far I haven't seen a drop of anything come from the exhaust. There is a small thermostat leak though. Letting it cool off and going to change that out with some RTV for waterpumps/thermostats and hopefully it goes away.

The valves, I wasn't sure if it needed any lash or not. It's a hydraulic flat tappet cam. I turned it until the lifters were at their lowest spot and turned the bolt until the pushrod had just a little bit of pressure. In any event, the "knock" went away so I'm suspecting that it's hydraulic lifters. Could be wrong which is why I made sure they all had about the same amount of pressure. Also there wasn't a "lock" on them. Just a bolt. Strangely, the smallest turn could make them really really tight so some of them took some back and forth to get it so there was only a little bit pressure on the pushrod. Maybe in the last 15,000 miles they came a little loose...

I think once it has a reman carb it will probably run a lot better. I was told it needs to get rebuilt so it'll probably be cheaper to get a reman. The brakes are a little soft too but I think that may be a vacuum issue. Double check that and hopefully get them working 100% again. It can take some pumping to stop. Power wise, I'd say it's 90-95% what it was a couple years ago. It's also doing good on gas again. I'd guess it's getting around 5 or so in town which is not bad.

Awesome nixtux! Glad to hear it's running good again. I would say that the screech was 100% bad fuel pump. Hopefully you got the rockers adjusted decent. With hydraulic lifters you have a small amount of room for error. With solid lifters you don't really have any.

That nasty port looks like a water jacket to me. The crud is just deposits from the water. I would have scraped out what I could and moved on. They are always ugly. If you look at the first head pic, the Intake Ports are on the left and the Exhaust Ports are on the right. They still have the headers attached over them.

A rebuilt Q-Jet sounds like the right way to go for your setup. That intake should work fine besides being heavy and limiting your high RPM's but will work better for low RPM torque. That's what you need on the street anyway so you're good.

Which LocTite did you get? (Red,Blue, etc) It's a little late now but what I use on Intake & Water Pump bolts in the Permatex Non-Hardening type. It's dark brown and feels like wet modeling clay when you put it on but keeps the bolts in place and liquids from oozing up the threads.

Axe

[nixtux]

Awesome nixtux! Glad to hear it's running good again. I would say that the screech was 100% bad fuel pump. Hopefully you got the rockers adjusted decent. With hydraulic lifters you have a small amount of room for error. With solid lifters you don't really have any.

That nasty port looks like a water jacket to me. The crud is just deposits from the water. I would have scraped out what I could and moved on. They are always ugly. If you look at the first head pic, the Intake Ports are on the left and the Exhaust Ports are on the right. They still have the headers attached over them.

A rebuilt Q-Jet sounds like the right way to go for your setup. That intake should work fine besides being heavy and limiting your high RPM's but will work better for low RPM torque. That's what you need on the street anyway so you're good.

Which LocTite did you get? (Red,Blue, etc) It's a little late now but what I use on Intake & Water Pump bolts in the Permatex Non-Hardening type. It's dark brown and feels like wet modeling clay when you put it on but keeps the bolts in place and liquids from oozing up the threads.

Axe

I'm still planning on getting Q-Jet but so far it just seems like the choke isn't working. I just have to hold the gas a little while it warms up to around 110-120F before it will maintain an idle.

The frustrating part is the exhaust leaks. All the hangers have broke so the exhaust just dangles and tings. The headers are hideous and there is small leaks right off the block. I'm torn between stock exhaust manifolds or getting the below headers. I'd really like to resolve the exhaust leaks so it has a nice even sound. I'm thinking I'll get headers this week instead of a reman. Next week try and have the exhaust fixed. New hangers and new piping from the Headers to the glass-packs. Just looking for suggestions on what headers to get or should I just convert it back to the exhaust manifolds.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220634886718&crlp=1_263602_263622&ff4=263602_263622&viewitem=&guid=99621b231290a0e2024374d3fe2fe8be&rvr_id=&ua=L*F%3F&itemid=220634886718

[nixtux]

I've just went over my 100 mile point. So far the oil is as clean as the day I added it. That stupid thermostat is still leaking. I torqued it to 25lbs (which is what is says in the haynes manual) well they say 20-30 so I figured 25 was a good number. I think I might buy the 18.00 rubber gasket and try that. On another note, a shop did the thermostat last time and said it will never leak again!!! BS. It leaked even after he put in a new gasket and RTV. I've been reading online and it seems to be a common issue with the 350. I got the water pump/theromostat RTV this last time and applied a even bead. Let it set for 10-15 minutes, put the thermostat housing on and torqued to 25lbs. Let it sit until today and as soon as it got to around 110F (temp) it had a small leak on the outside. At least it's not the other way/side because then it sits in the intake valleys.

Anyway I hooked up the timing light. I'm getting a nice lopey idle between 590-680RPM's. It's fairly consistent, it lopes down to 570-580 and jumps to 670-680 then back and so on. It is a lopey cam. The timing is at around 15deg. I'm not sure where it should be so my friend said to get it between 12-15. I'm pretty sure the idle should probably be a little higher. But that could be because of the carb (that spring in general.)

[Axe_1]

There should be a little screw on the side with a spring around it to adjust the idle. The point end should be resting on a metal tab. To make sure you have the right one, open the throttle plate by hand and the screw assembly should move with it. Turning that a small amount in will raise the idle, out will lower it.

Lopey is good but if the RPM's still jump up and down at he right idle speed (750-900 depending on the cam, compression, ect) you more than likely still have a vacuum leak. Look for an open port on the intake and base of the carb. The large one one the carb between 1/4-1/2 inch in dia should be the float bowl vent. That should be vented to the charcoal cannister, or just left open for now.

How big was the spring that fell off? There should be 2 large springs used for the throttle return, one inside the other.

Axe

[nixtux]

There should be a little screw on the side with a spring around it to adjust the idle. The point end should be resting on a metal tab. To make sure you have the right one, open the throttle plate by hand and the screw assembly should move with it. Turning that a small amount in will raise the idle, out will lower it.

Lopey is good but if the RPM's still jump up and down at he right idle speed (750-900 depending on the cam, compression, ect) you more than likely still have a vacuum leak. Look for an open port on the intake and base of the carb. The large one one the carb between 1/4-1/2 inch in dia should be the float bowl vent. That should be vented to the charcoal cannister, or just left open for now.

How big was the spring that fell off? There should be 2 large springs used for the throttle return, one inside the other.

Axe

I did some adjusting with the idle. I got it between 780-860RPM at temp. I had to turn the screw a couple turns. Not sure how it drives with the new idle. I figure I'll wait until there is little traffic just in case it decides to idle really high making it difficult to stop. I'll check on the vacuum lines tomorrow. I have to redo the thermostat as well. Hopefully the expensive rubber gasket will seal it up properly.

The spring was white and yellow-ish and a little over a inch high. About the diameter of a nickle.

[Axe_1]

That spring sounds like the inside Throttle Return Spring. They fall off all the time when installing the carb. The outer one is green or blue and more like a Quarter size in diameter. (again from memory)

If the idle is right but it's hard to stop there are 2 main ways to fix it.

1. External Vacuum Cannister - (quick fix) Mount it somewhere under the hood and run between the main intake port and the brake booster for extra vacuum.

2. Torque Converter - (Best solution) Larger stall speed will allow the tranny to slip at the higher RPM. Just remember that any slippage is friction and adds heat to the tranny so it's important to select the right one for the Vehicle Weight, Engine HP/RPM Range, and Gear Ratio/Tire Diameter.

Actually the BEST solution would be to add both as you have the time and money.

I have a Darrell Young 2600 Converter in the M/C and it's perfect for the heavy car with a potato cam. It's Flash RPM is more like 2800 in this setup. I would also recommend a Trans Cooler. It's like a tiny radiator. Cheap and very easy to install but could save you thousands in transmission repairs.

Axe

[nixtux]

That spring sounds like the inside Throttle Return Spring. They fall off all the time when installing the carb. The outer one is green or blue and more like a Quarter size in diameter. (again from memory)

If the idle is right but it's hard to stop there are 2 main ways to fix it.

1. External Vacuum Cannister - Mount it somewhere under the hood and run between the main intake port and the brake booster for extra vacuum.

2. Torque Converter - (Best solution) Larger stall speed will allow the tranny to slip at the higher RPM. Just remember that any slippage is friction and adds heat to the tranny so it's important to select the right one for the Vehicle Weight, Engine HP/RPM Range, and Gear Ratio/Tire Diameter.

Actually the BEST solution would be to add both as you have the time and money.

I have a Darrell Young 2600 Converter in the M/C and it's perfect for the heavy car with a potato cam. It's Flash RPM is more like 2800 in this setup. I would also recommend a Trans Cooler. It's like a tiny radiator. Cheap and very easy to install but could save you thousands in transmission repairs.

Axe

I got to thinking on the vacuum lines, I think I may have mixed two of the smaller lines on the carb. I've been meaning to switch them and see if the brake presure returns. I checked the metal line that connects to the rear of the carb and it's tight. The fluid is full as well. I know the brakes are good because they were grounded out about 500 (maybe 1000) miles ago. The rear drums anyway. It was winter and they kept locking up. Turned out to be debry got stuck between the drum. Also they brakes were all replaced around 15,000 miles ago.

I've heard some complaints about B&M. It has a B&M 2000 stall. The main complaint is they don't take a lot of power. In this setup, I don't think it'll be a big issue. Albeit, the current stall on it is enough to make it jump 5-7MPH between shifts at WOT. I've been reading about doing a blow through carb. Considering one day, maybe trying to do a small turbo on it. It's a ugly orange 73' rust bucket but it's a fun truck to drive. First things first, brakes, exhaust leaks, and a reman carb. Maybe down the road, some plumbing for a small 8 or so PSI turbo. Assuming it can even handle it. It seems like fairly cheap and easy mod anyway. It has flat top pistons, 9:1 compression, ect ect. I'm not a mechanic. This stuff is a hobby that I enjoy and would like to actually understand it better.

I redid the timing light at temp and ran it up to around 2800RPM's and it looked like the timing was at around 25Deg. I think that may be a little too advanced. I'll probably back the distributer a little bit. I was reading comp cams camshaft PDF and they said to spec it stock and maybe advance it by 4 after that... I think that's what they meant. I got inturrupted when I was reading. But if it's suppose to be advanced 4degs, does that mean it should be between 12-16 since the truck should be (stock) around 8-12. FYI, I think it says 8-12 on the sticker under the hood.

[Axe_1]

12-16 sounds right on the timing. Not sure what the total advance should be off hand, but if you stay in that range at idle there is a sweet spot that will accelerate well, not overheat, and still crank with the starter.

Not a big fan of B&M, not because they are bad but because they charge a lot and are directed at the masses. The 2,000 stall may not be quite enough for this engine, but adding a vacuum canister should help that. There are 2 different ways to rate the stall and most companies like B&M use the one that sounds the best.

I wouldn't consider a boost unless I was sure what pistons were in there. I know you want to go small on it, but I personally wouldn't add any with stock Cast Aluminum pistons. You really need Hypereutectic or Forged Aluminum if you want it to last any time at all. I'd say getting the carb, timing, and vacuum right will give you as much power as you're looking for.

If you still have the stock points distributor they make different advance kits to adjust the rate of advance, but again, I'd just throw in a stock HEI, change out those wires, and be done with that.

The main difference with those vacuum lines to the carb is if the ports are above or below the throttle plate. Work the throttle by hand again and you can just look to see where the throttle plate shaft goes through the carb.

If they are below that they draw a vacuum all the time, and if they are above they draw when the throttle plate is open. (I think I got that right) The brakes need vacuum all the time, if that helps.

Axe

Forgot to add that after that I would consider my gear ratio before a boost.

Also, I've had a lot more fun in a beat up project car/truck than I ever had in something too nice to run hard.

[nixtux]

12-16 sounds right on the timing. Not sure what the total advance should be off hand, but if you stay in that range at idle there is a sweet spot that will accelerate well, not overheat, and still crank with the starter.

Not a big fan of B&M, not because they are bad but because they charge a lot and are directed at the masses. The 2,000 stall may not be quite enough for this engine, but adding a vacuum canister should help that. There are 2 different ways to rate the stall and most companies like B&M use the one that sounds the best.

I wouldn't consider a boost unless I was sure what pistons were in there. I know you want to go small on it, but I personally wouldn't add any with stock Cast Aluminum pistons. You really need Hypereutectic or Forged Aluminum if you want it to last any time at all. I'd say getting the carb, timing, and vacuum right will give you as much power as you're looking for.

If you still have the stock points distributor they make different advance kits to adjust the rate of advance, but again, I'd just throw in a stock HEI, change out those wires, and be done with that.

The main difference with those vacuum lines to the carb is if the ports are above or below the throttle plate. Work the throttle by hand again and you can just look to see where the throttle plate shaft goes through the carb.

If they are below that they draw a vacuum all the time, and if they are above they draw when the throttle plate is open. (I think I got that right) The brakes need vacuum all the time, if that helps.

Axe

Forgot to add that after that I would consider my gear ratio before a boost.

Also, I've had a lot more fun in a beat up project car/truck than I ever had in something too nice to run hard.

I'm not sure what kind of pistons. Maybe there is a receipt that'll shed some light but I have to get that from the guy who was going to buy the truck. A basic runover. The work was done in 2002, the truck had 82,300mi. It has 98,680mi now.

Rebuilt 350 with .03 Block Bore (355)
Rods & mains .010
Comp Cam 242 Extreme Energy
Comp Cams Double Roller Timing Chain
B & M Torkmaster 2000 High Stall Torque Converter
Rebuilt TH350 /w shift kit
Elgin valve springs
Flattop pistons
Quadro-Jet 750cfm 4-barrel carb
Electric choke

I think the gear ratio is 3.79 (something like that.) It's a GM 9 bolt rear-end I think. I don't have the papers and I haven't looked at them in a couple years.

[robertisaar]

If they are below that they draw a vacuum all the time, and if they are above they draw when the throttle plate is open. (I think I got that right) The brakes need vacuum all the time, if that helps.

this is correct. been a while since i've dealt with carbs, but the venturi effect(IIRC) will draw vacuum above the plate when open, but under the plate is in vacuum at all times(except when WOT, but the engine is still drawing air, therefore fuel, as well).

[nixtux]

I'm not sure what kind of pistons. Maybe there is a receipt that'll shed some light but I have to get that from the guy who was going to buy the truck. A basic runover. The work was done in 2002, the truck had 82,300mi. It has 98,680mi now.

Rebuilt 350 with .03 Block Bore (355)
Rods & mains .010
Comp Cam 242 Extreme Energy
Comp Cams Double Roller Timing Chain
B & M Torkmaster 2000 High Stall Torque Converter
Rebuilt TH350 /w shift kit
Elgin valve springs
Flattop pistons
Quadro-Jet 750cfm 4-barrel carb
Electric choke

I think the gear ratio is 3.79 (something like that.) It's a GM 9 bolt rear-end I think. I don't have the papers and I haven't looked at them in a couple years.

Found this on a old post of mine. Has the cam specs too.

1973 GMC Super Custom

350 .03" bore (355)
rods and main .010"

From Comp Cams Limited Warranty Card

Value lift .47 .480
Duration .006

value timing open close
at 0..6 INT 28 BTDC 60 ABDC
EXH 74 BBDC 26 ATDC

Cam specs
AT 106 Intake center line
Intake Exhaust
Duration .050 224 230
Lobe lift .3180 .3200
Lobe separation 110.0

Flattop pistons - 9/1 Compression
Comp Cam 242 Extreme Engery
Rochester quadrajet Carb
Headers 2 1/4 pipes /w mufflers (not too loud)

T350 /w shift kit
Torkmaster 2000

3.73 Gears - 12 bolt rear-end